This invention relates to an electric rotary machine equipped with a stator coil including sequentially connected conductor segments (which is also referred to as “serial-joint segmental stator coil”, in the following description), which is preferably applicable to an automotive vehicle.
According to the idle stop system recently employed for automotive engines, the engine is frequently required to stop and restart. Large current is required for restarting the engine. Thus, for the idle stop system, using an excellent starter motor capable of surely supplying large current is essentially important.
In this respect, a serial-joint segmental stator coil is simple in the wiring arrangement at its coil end, large in the slot space factor, compact in the size, and light in the weight. Accordingly, the serial-joint segmental stator coil has excellent heat radiation properties and is preferably employable in an alternating-current motor supplying large current to frequently restart the engine.
Enlarging the cross-sectional area of a conductor segment in the stator coil is effective in increasing the current flowing in an electric rotary machine. However, difficulty in bending the conductor segment will limit the increase in the cross-sectional area of a conductor segment.
Meanwhile, to increase the output of an automotive electric rotary machine and also reduce the wiring loss in this machine, not only increasing the current but also increasing the voltage will be necessary. In other words, the turn number of the coil will be increased inevitably.